Casting sprocket-wheels.



No. 694,395. Patented Mar. 4, I902.

C. W. LEVALLEY.

CASTING SPBOCKET WHEELS.

' (Application filed Jan. 7, 1899.) I (No Model.) 2 Sheets'Sheat I.

[NVENTQR Patented Mar. 4, 1902. c. w. LEVALLEY.

CASTING SPRUCKET WHEELS.

(Application filed Jan. 7, 1899.)

2 sheets sheet 2.

(No Model.)

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CHRISTOPHER W. LEVALLE Y,

PATENT OFFICE.

OF MILWAUKEE, WISCONSIN.

CASTING SPROCKET-WH EELS.

SPECIFICATION forming part of Letters Patent No. 694,395, dated March 4,1902.

Application filed January '7, 1899. Serial No- '701,4.42. (No model.)

To (tZZ whom it may concern:

Be it known that I, CHRISTOPHER W. LE-

VALLEY, a citizen of the United States, residing at Milwaukee, in thecounty of Milwaukee and State of IVisconsin, have invented cer' tain newand useful Improvements in Casting Sprocket -Wheels, of which thefollowing is a specification, reference being had therein to theaccompanying drawings.

This present invention relates to the manufacture of toothedgear-wheels, and more particularly to that kind of such wheels known assprocket-wheels, which are used in connection with drive-chains forpower-transmitting purposes.

It has been demonstrated that sprocketchains are subject to excessivewear at two parts particularly, these being the side or working faces ofthe teeth and the peripheral portions of the wheel adjacent to the basesof the teeth, asit is with these parts of the wheel that thearticulating portions of the chain particularly engage.

My invention has for its object to produce a mold for use in the castingof toothed wheels, particularly sprocket wheels, which 'mold comprises aseries of separate and independent chills for the individual teeth ofthe wheels, these chills being constructed as will be specificallypointed our hereinafter and so that they operate to chill, and thereforeharden, the surfaceof the metal of the wheel at those points or portionswhere the wear is the greatest that is to say, the working faces of thesprocket-teeth and also the periphery of the wheel adjacent to the basesof the teeth.

It is well understood that in order to secure the least friction andutmost efficiency the pitch of the drive-chain and of the wheel withwhich it engages should be the same. As the engaging faces of the teethof the wheel wear away the pitch of the wheel is changed,. and thereforeit has been proposed to chill the working faces of the teeth to reduceas far as possible the wear of the teeth. It is also evident that whenthe wearing-s11 rfaces of the periphery of the wheel adjacent to thebases of the teeth and with which the cross parts of the link engagewear ,away the pitch of the wheel will be varied or the properengagement of the chain with the wheel will be interfered with, for thereason that the bearingsurfaces for the links of the chain upon theperiphery of the wheel will have changed their relation to .the properengaging surfaces for the links of the chain with the teeth of thewheel. The proper relations of these two important wearing or bearingsurfaces should be maintained in all wheels, whatever their size ornumber of teeth, made for a particular size and kind of chain, and theserelations should be maintained as nearly as possible throughout the lifeof the wheel, and I therefore construct my mold so that theseWearingsurfaces shall be chilled and hardened during the process ofcasting the wheel.

In the accompanying drawings, Figure l is a perspective view of anindividual chill such as I have invented and used in the working of myinvention. Figs. 2 to 5, inclusive, are detached plan views of molds forthe casting of sprocket-wheels of different sizes embodying myinvention, Fig. 2 being for a wheel provided with six sprocket-teeth,Fig. 3 for a wheel with twelve sprocket-teeth, and Fig. 5 for a Wheelwith twenty-four sprocket-teeth. Fig. 4 illustrates a feature of theinvention, which will be later described. Fig. 6 is a plan view of aportion of a wheel made according to my invention and in engagement withwhich I have represented a short section of drive-chain. Fig. 7 is acentral Vertical section of a mold for casting a wheel embodying myinvention.

Referring first to Fig. 6, A represents the body of a sprocket-wheel,and O the teeth thereof. 13 B indicate the links of a sprocket or drivechain adapted to engage with the wheel. For the purposes of illustrationI have chosen a well-known type of chain in which each link is of asinglepiece, having opposite side bars, an end bar at one end, and ahook at the opposite end. In the drawings, b b indicate the crossarticulating parts of the chain, which are in this instance composed ofa side bar and an engaging hook. The pitch of the chain is the distancebetween the axes of the articulating parts, and the pitch of the wheelwith which this chain engages should be the same as that of the chain.The cross parts of the chain engage with the wearingsurfaces of theteeth at c, and I have by the dotted line H indicated a circle whichincludes the wearing-surfaces c of the teeth,

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wheel at the bases of the teeth with which the cross portions of thechain engage. The dotted line I indicates a circle struck from thecenter of the wheel, which cuts these wearing portions 0, and which Iterm the base-circle. As pointed out hereinbefore, it is necessary tothe proper working of the chain upon the wheel that the wear at theportions 0' c of thechain should be reduced to a minimum, and theseportions of the wheel are chilled by means which I will presentlydescribe. It is evident that the distance between the circles H and Itaken upon any radial line must be the same whatever the size of thewheelthat is, whether it have many or few teeth because it is thesurfaces 0 which operate to support the chain and so sustain it that thearticulating parts thereof shall be maintained in the pitch-circle H andshall properly engage with the wearing-surfaces c of the wheel. This istrue'notwithstanding the fact that the relations of the teeth to eachother vary with each difference in the size of the wheel and the numberof teeth which it has. This is clearly illustrated in Figs. 2, 3, and 5,where the pattern E may be taken to represent the wheel for the purposesof this consideration.

In the drawings, E represents the pattern, whichis of the shape of thewheel desired to be produced and which is inserted in the sand(represented at F) in the way commonly followed in the art of castingmetal.

'D represents a chill, which is preferably of the form and constructionrepresented in Fig. 1.

In operating my invention the pattern E is properly placed and thechills are then placed around it, as represented in Figs. 1, 2, 5, and7, one being placed over each tooth e of the pattern. The sand is thenpacked around the pattern and the chills in the usual way and thepattern finally removed, leaving the chills firmly embedded in the sandand con.- stituting a part of the mold. Each chill consists of a blockof suitable material formed at one end with a recess adapted toaccurately fit the tooth of the wheel which is to be formed. The innerwalls cl of this recess operate to chill the opposite working faces 0 ofthe teeth 0 of the sprocket-wheel. The recessed end of the chill isformed with ends d cl, which extend laterally beyond the recess andoperate to form and to chill the peripheral wearing-surfaces c of thewheel adjacent to the bases of the teeth. The inner portions of the ends(1 of the chill-that is, the portions which are next to the recessarecurved, while the outer or edge portions are substantially fiat andapproximately at right angles to a line which passes longitudinallythrough the center or axis of the recess in the chill. As the chill isan integral structure, the re lations of the surfaces thereof which formand which chill the parts 0 c of the wheel cannot vary relative to eachother.

By using chills of the construction shown and described and one for eachseparate tooth of the wheel to be formed it is possible to use a singleset of chills in the casting of wheels of different sizesnotwithstanding the fact thatthe positions and relations of the teethrelative to each other vary with each change in the size of the wheel.This is clearly indicated in Figs. 2, 3, and 5.

The advantages incident to my invention as thus far described will beclearly'understood. Asingle form of chill may be provided for themanufacture of all wheels to be used with chains of a particular typeand size no matter what the size of the wheel may be. The chills operateto produce a wheel with hardened or chilled surfaces at the importantwearing parts cc, and these parts are always formed in proper relationto each other whatever he the size of the wheel, and, further, the wheelproduced according to my invention may be run in either direction, theopposite sides of the teeth being counterparts of each other.

By reference to Figs. 1 and 7 it will be seen that the chills are muchthicker than are the teeth which they form. By thickness -I refer to thedimension indicated by the double arrow D of Fig. 1. Theadvantagesincident to this construction are that when a sand mold isused the sand may be rammed against the vertical or end surfaces cl ofthe chills as well as between the side faces thereof, both above andbelow the pattern E, and this operates to firmly hold the chills inplace, reducing danger of accidental displacement to a minimum. In Fig.7 the chills are represented as being supported upon a board G.

It is often desirable in making sprocket wheels for a given style andsize of chain that certain of the wheels should be a little larger thancertain others, and-thus have a slightlygreater pitch. Thus it is betterto have the driving-wheel a little larger than the driven wheel. Again,'if a new wheel is to be used in connection with an old chain or onewhich has become worn it is desirable that the wheel should be a triflelarger than a new wheel for the same chain. By means of my invention itis a very simple matter to slightly increase the size of the wheels andstill make use of the same chills which are employed for wheels ofslightly-smaller size. How this may be done is illustrated in Fig. 4t ofthe drawings. The same pattern E is employed as when it is desired tomake a wheel of normal size and pitch; but the chills D are supported ata slight distance away from or beyond the teeth e of the pattern. Inorder to thus support the chills and to properly place them relative tothe teeth E, I prefer to insert between the side faces of the'teeth andthe faces cl of the chills liners or spacing -strips 6'. These strips orpieces may be of paper,w0od,

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metal, or other suitable material and merely operate to temporarilyholdthe chills in proper position relative tothe pattern until they havebeen set in the sand, after which such pieces are removed along with thepattern E. Other means for supporting the chills at a slight.

they are used, and the accuracy with which slight changes in thepositions of the chills may be made, are apparent.

It will be observed that the teeth of sprocketwheels which my inventionis adapted to produce are relatively far apartand .that the chills areeach formed with end faces d,which.

extend laterally from the teeth,and that these laterally-extending facesare of a breadth less than half the space between the bases of the teethofv the wheels in the casting of which they are adapted to be used, withthe result that while the chills operate to chill and harden theperipheral bearing-surfaces c of the wheel for a sufficient distance oneither side of each tooth the chills may still be used in the casting ofwheels of different sizes without interfering one with the other,,aswill be clearly seen as by comparison of Figs. 2, 3, and 5.

Having thus described my invention, what I claim, and desire to secureby Letters Patcut, is-

1. For the casting of sprocket-wheels a series of, chills one for eachtooth of the wheel, the chills being duplicates one of the other, andeach recessed at one end and formed with the inner walls of the recessesarranged to form and chill the working sides of the teeth, and alsoformed with end faces d, which extend laterally beyond the recesses inthe chills and are arranged to form and to chill the periphery of thewheel adjacent to the bases of the teeth, the outer or edge portions ofwhich end faces are substantially flat, substantially as set forth.

2. For the casting of wheels having teeth which are relatively farapart, a series of chills, one for each tooth of the wheel'tobe formed,the chills being duplicates one of the other and each recessed at one'end whereby it forms and chills the working sides of a tooth, and alsoformed with end faces which extend laterally from the recess therein andwhich form and chill the parts of the periphcry of the wheel adjacent toand on either side of each tooth, the width of the saidlaterallyextending end faces of the chills being less than half thedistance between the bases of the teeth in the casting of which thechills are used, and the outer or edge-portions of the I saidend facesbeing substantially flat, substantially as set forth.

3. For use in the castingof sprocket-wheels a series of recessed chills,one for each tooth of the wheel, the chills being formed with end facescl adapted to form and chill portions of the periphery of the wheeladjacent to the bases of the teeth, these faces of the chills being of athickness greater than the thickness of the teeth which the chills form,and the outer or edge portions of such chill-faces being substantiallyflat, substantially as set forth.

4. The combination with a toothed pattern, of a series of recessedchills,one for each tooth arranged to fit over the teeth of the pattern,and means for supporting the chills in position toembrace the teeth ofthe pattern, but at a slight distance beyond the same, sub stantially asset forth.

5. The combination with a toothed pattern, of a series of recessedchills, one for each tooth and removable liners or spacingfpiecesarranged between the teeth of the pattern and the walls of the recessesof the chills whereby the positions of the chills relative to thepattern may be slightly varied, substantially as set forth.

. In testimony whereof I affix my signature in presence of twowitnesses.

CHRISTOPHER W. LEVALLEY.

